This invention relates generally to a device for inserting a lance through a side opening in a pressurized container, in particular a blast furnace. More particularly, this invention relates to a device for inserting, from a support structure, a lance axially through a side opening in a pressurized container, in particular a blast furnace, which is able to compensate for level variations between the side opening in the pressurized container and the support structure.
A device of this type is known from U.S. Pat. No. 3,643,508. It is used for inserting a measuring lance, for measuring the temperature and taking samples of gases, into a blast furnace and comprises a support bench and three supports for the lance. A support carriage can slide along the support bench and the rear end of the lance is articulated therein. A front bearing for the lance is arranged in proximity to a sealing and closing member. An inner support for the lance, is arranged behind the sealing and closing member on the inner side of the blast furnace.
It is to be recalled that for a modern blast furnace, such a measuring lance may have a length of 8 meters or more. The object of the internal support is to reduce the overhanging length of the lance when the lance is introduced through the sealing and closing member inside the blast furnace. In other words, the purpose of this internal support is to reduce the mechanical stresses to which the probe is exposed when overhanging this internal support. Such an internal support for a blast furnace probe is described in detail in U.S. Pat. No. 4,471,664.
In the device known from U.S. Pat. No. 3,643,508, the support bench for the lance is supported, on the blast furnace side, on the support structure by a height-adjustable support. The front support for the lance is integral with the support bench. When the side opening undergoes a level variation with respect to the support structure, which may be due to a thermally induced expansion of the blast furnace, the height-adjustable support of the support bench should be adjusted in order to compensate for this level variation. For a person skilled in the art, it is clear that this adjustment constitutes a time consuming and costly task which it is desirable to eliminate. Furthermore, after adjustment of the level of the front end of the supporting bench, the three support points of the lance are no longer aligned. This indicates that the lance supported by the support carriage and the front support no longer bears on the internal support. This results in the lance undergoing mechanical stresses which are much greater than intended.